Methods for producing silicon carbide fibers

Abstract

Methods of producing silicon carbide fibers. The method comprises reacting a continuous carbon fiber material and a silicon-containing gas in a reaction chamber at a temperature ranging from approximately 1500° C. to approximately 2000° C. A partial pressure of oxygen in the reaction chamber is maintained at less than approximately 1.01×10 2 Pascal to produce continuous alpha silicon carbide fibers. Continuous alpha silicon carbide fibers and articles formed from the continuous alpha silicon carbide fibers are also disclosed.

What is claimed is: 
     
       1. A method of producing alpha silicon carbide fibers, comprising:
 reacting a carbon fiber material and a silicon-containing gas in a reaction chamber at a temperature ranging from approximately 1500° C. to approximately 2000° C. and a pressure of about 1 atmosphere; and 
 maintaining a partial pressure of oxygen in the reaction chamber of less than approximately 1.01×10 2  Pascal to produce alpha silicon carbide fibers. 
 
     
     
       2. The method of  claim 1 , wherein reacting a continuous carbon fiber material and a silicon-containing gas in a reaction chamber comprises reacting the continuous carbon fiber material and silicon monoxide in the reaction chamber. 
     
     
       3. The method of  claim 2 , wherein reacting the continuous carbon fiber material and silicon monoxide in a reaction chamber comprises forming the silicon monoxide in situ in the reaction chamber. 
     
     
       4. The method of  claim 3 , wherein forming the silicon monoxide in situ in the reaction chamber comprises reacting silicon dioxide and silicon in the reaction chamber. 
     
     
       5. The method of  claim 1 , wherein reacting a carbon fiber material and the silicon-containing gas in the reaction chamber comprises reacting a pitch-based resin and silicon monoxide in the reaction chamber. 
     
     
       6. The method of  claim 1 , wherein reacting a carbon fiber material and a silicon-containing gas in a reaction chamber comprises reacting a polyacrylonitrile (PAN) based carbon fiber and silicon monoxide in the reaction chamber. 
     
     
       7. The method of  claim 1 , wherein reacting a carbon fiber material and a silicon-containing gas in a reaction chamber at a temperature ranging from approximately 1500° C. to approximately 2000° C. comprises reacting the carbon fiber material and the silicon-containing gas at a temperature ranging from approximately 1600° C. to approximately 1800° C. 
     
     
       8. The method of  claim 1 , wherein maintaining the partial pressure of oxygen in the reaction chamber of less than approximately 1.01×10 2  Pascal to produce alpha silicon carbide fibers comprises producing the alpha silicon carbide fibers comprising a converted layer of alpha silicon carbide on the carbon fiber material, where the converted layer has been converted from carbon to alpha silicon carbide. 
     
     
       9. The method of  claim 1 , wherein maintaining a partial pressure of oxygen in the reaction chamber of less than approximately 1.01×10 2  Pascal to produce alpha silicon carbide fibers comprises producing fully converted alpha silicon carbide fibers comprising alpha silicon carbide surrounding a hollow core. 
     
     
       10. The method of  claim 1 , wherein a pressure within the reaction zone is maintained at a positive pressure of from approximately 1 psig to approximately 10 psig above atmospheric pressure to prevent an external atmosphere from entering into the reaction chamber. 
     
     
       11. The method of  claim 1 , wherein a vapor pressure of silicon monoxide species in the reaction chamber is maintained at approximately 1 atm. 
     
     
       12. The method of  claim 1 , wherein the alpha silicon carbide fibers comprise filaments of alpha silicon carbide. 
     
     
       13. The method of  claim 1 , wherein the carbide fibers reacted within the reaction chamber include continuous carbon fibers, and the produced alpha silicon carbide fibers comprise continuous alpha silicon carbide fibers. 
     
     
       14. A method of producing silicon carbide fiber, comprising:
 drawing a continuous carbon fiber material into a reaction zone of a reaction chamber, the reaction zone comprising silicon dioxide, silicon, and a carrier gas; and 
 heating the reaction zone comprising silicon dioxide, silicon, and the carrier gas to a temperature ranging from approximately 1600° C. to approximately 1800° C. and at a pressure of about 1 atmosphere, while maintaining a partial pressure of oxygen of less than approximately 1.01×10 2  Pascal to produce continuous alpha silicon carbide fibers. 
 
     
     
       15. The method of  claim 14 , wherein heating the reaction zone comprising the silicon dioxide, silicon, and the carrier gas to a temperature ranging from approximately 1600° C. to approximately 1800° C. comprises reacting silicon dioxide and silicon to form silicon monoxide and reacting the silicon monoxide with carbon of the carbon fiber material to produce the continuous alpha silicon carbide fibers. 
     
     
       16. The method of  claim 14 , wherein a pressure within the reaction zone is maintained at a positive pressure of from approximately 1 psig to approximately 10 psig above atmospheric pressure to prevent an external atmosphere from entering into the reaction zone. 
     
     
       17. The method of  claim 14 , wherein a vapor pressure of silicon monoxide species in the reaction zone is maintained at approximately 1 atm. 
     
     
       18. The method of  claim 14 , wherein the alpha silicon carbide fibers comprise filaments of alpha silicon carbide. 
     
     
       19. A method of converting carbon fiber to alpha silicon carbide fiber, the method comprising:
 feeding a carbon fiber material through a reaction chamber, the reaction chamber including a silicon-containing gas, the reaction chamber being at a temperature ranging from approximately 1500° C. to approximately 2000° C. and a pressure of approximately 1 atmosphere, wherein a partial pressure of oxygen in the reaction chamber is less than approximately 1.01×10 2  Pascal; 
 such that the carbon fiber material reacts with the silicon-containing gas, converting the carbon fiber material to alpha silicon carbide fiber, the alpha silicon carbide fiber comprising filaments of alpha silicon carbide. 
 
     
     
       20. The method of  claim 19 , wherein reacting the continuous carbon fiber material and silicon monoxide in a reaction chamber comprises introducing silicon monoxide into the reaction chamber containing the carbon fiber material so that the carbon fiber material reacts with the silicon monoxide. 
     
     
       21. The method of  claim 19 , wherein maintaining the partial pressure of oxygen in the reaction chamber of less than approximately 1.01×10 2  Pascal to produce alpha silicon carbide fibers comprises producing partially converted alpha silicon carbide fibers comprising a converted layer of alpha silicon carbide surrounding a core of unconverted carbon fiber material.